Dual drive transmission

ABSTRACT

A transmission is provided for converting rotary input into an oscillating output. The transmission includes a housing with an input shaft and an output shaft, and a series of gears interconnecting the shafts. The gears include a pair of rack gears on opposite sides of an output pinion mounted on the output shaft. The rack gears are held in meshing engagement with the output pinion by a carrier which is mounted upon a floating bushing on the output shaft. The floating bushing allows the rack gears and rack carrier to move side-to-side relative to the output shaft, thereby equalizing the load on the rack gears and preventing binding between the teeth of the rack gears and the teeth of the output pinion.

BACKGROUND OF THE INVENTION

Conventional clothes washing machines include an agitator whichoscillates during the washing cycle to facilitate the cleaning ofclothes. The oscillation of the agitator is achieved through a series oflinkages and gears. More particularly, an input shaft is connected to adrive motor and an output shaft is connected to the agitator. Aneccentric gear is driven through an arcuate path by a series of gearsconnected to the input shaft. The eccentric gear is operativelyconnected to the output shaft, such that the rotary motion from theinput shaft is converted into the oscillating motion of the agitator.The off-center linkages require a counterweight for balance. Thenonalignment of the shafts produces undesirable side loading on theshafts and gears. The off-center shafts and counterbalance alsonecessitate a larger transmission housing.

A substantially different washing machine transmission is disclosed inU.S. Pat. Nos. 2,161,604 and 2,222,329 issued in the name of Watts. TheWatts patents show opposing rack gears operatively connected tocoaxially aligned input and output shafts to convert the rotary motionof the input shaft to an oscillation motion for the output shaft andconnected agitator in a clothes washing machine. However, the devicesdisclosed in the Watts' patents are not believed to have been evercommercialized due to a problem of binding between the rack gears andthe output pinion. Such binding necessarily resulted from the lack ofradial or side-to-side movement of the rack gears relative to the outputpinion.

Accordingly, a primary objective of the present invention is theprovision of an improved dual drive transmission which converts rotarymovement to oscillating movement.

A further objective of the present invention is the provision of a dualdrive transmission for a clothes washing machine having a reduced size,without reducing load carrying capabilities.

Another objective of the present invention is the provision of a dualdrive transmission wherein the shafts are co-axially aligned and thegears are equally spaced from the shaft axes.

A further objective of the present invention is the provision of a dualdrive transmission wherein gear loading is equalized.

Another objective of the present invention is the provision of rackgears which convert rotary motion to oscillating motion without binding.

Still another objective of the present invention is the provision of animproved dual drive transmission normally having pairs of opposite gearson opposite sides of the drive shaft, and wherein the gears on one sideof the shaft may be removed to provide a single drive transmission forreduced capacity machines having lesser power requirements.

A further objective of the present invention is the provision of animproved transmission having an anti-backup mechanism.

These and other objectives will become apparent from the followingdescription of the invention.

SUMMARY OF THE INVENTION

A dual drive transmission is provided to convert rotary action tooscillating action. The transmission can be used on appliances, such asclothes washing machines, wherein both rotary and oscillating action areutilized during the wash cycle. The transmission includes a housinghaving a removable cover. An input shaft is journaled into the housingand provides rotary motion to the transmission. An output shaft isjournaled into the cover and provides an oscillating motion to theagitator of the washer. A series of gears are operatively mounted inmeshing combination between the input shaft and the output shaft withinthe housing. The gearing includes an output pinion attached to theoutput shaft and a pair of rack gears positioned on opposite sides ofand in mesh with the output pinion. A rack carrier having an invertedU-shape has side walls which slidably engage the outer sides of the rackgears to retain the rack gears in mesh with the output pinion. The rackcarrier is mounted upon a floating bushing which is pivotally mountedupon the output shaft, and is movable side-to-side relative to theoutput shaft. The side-to-side movement of the bushing allows the rackcarrier and the rack gears to move side-to-side relative to the outputpinion, thereby preventing binding between the rack gears and the outputpinion. Thus, loading on the rack gears is equalized.

DETAILED DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a washing machine.

FIG. 2 is a sectional view taken along lines 2--2 of FIG. 1.

FIG. 3 is a sectional view taken along lines 3--3 of FIG. 2.

FIG. 4 is a sectional view taken along lines 4--4 of FIG. 3, with thecrank gears removed for clarity.

FIG. 5 is a sectional view taken along lines 5--5 of FIG. 3.

FIG. 6 is a sectional view taken along lines 6--6 of FIG. 4.

FIG. 7 is a view similar to FIG. 3 with the rack gears and rack carrierremoved for clarity.

FIGS. 8 and 9 are sectional views similar to FIG. 6 showing the rackgears at opposite ends of an oscillating stroke.

FIG. 10 is a perspective view of the underside of the rack gears andrack carrier.

FIG. 11 is a partial perspective exploded view showing the rack carrier,the floating bushing, and the output shaft.

FIG. 12 is a perspective view of the anti-backup mechanism of thepresent invention.

FIG. 13 is a sectional view taken along lines 13--13 of FIG. 4, andshowing the anti-backup mechanism of the present invention.

FIG. 14 is a sectional view similar to FIG. 6 showing an alternativeembodiment single drive transmission.

BRIEF DESCRIPTION OF THE DRAWINGS

A clothes washer is generally designated in the drawings by thereference number 10. The washer 10 includes a cabinet 12 with an accessopening 14 and a door 16 movable between and open and closed positionsrelative to the access opening 14. The washing machine 10 includes avertical axis rotatable perforated basket 18 mounted within a tub 20.The tub 20 includes a drain outlet 22. An agitator 24 is operativelymounted within the basket 18.

A transmission housing 26 and a brake housing 28 are mounted to the tub20 by a plurality of braces 30. A drive pulley 32 is operativelyconnected to the brake within the brake housing 28 and to the drivetrain of the transmission in the transmission housing 26. A motor (notshown) is drivingly connected to the pulley 32 with a conventional drivebelt (not shown).

The above-described components of the washing machine 10 areconventional, and do not constitute a part of the present invention.

The transmission housing 26 includes a lower casing 34 and a removableupper cover 36. Preferably, the cover 36 is threadably mounted upon thecasing 34, as seen in FIG. 4. The transmission includes an input shaft38 and an output shaft 40. The input and output shafts 38 and 40 arecoaxially aligned. The input shaft 38 extends rotatably into the lowertransmission casing 34 and is drivingly connected to the pulley 32,which imparts rotational movement to the input shaft 38. The outputshaft 40 extends rotatably through the transmission cover 36 and isdrivingly connected to the input shaft 38 through a series of gears.

The gear train of the transmission includes an input pinion 42 mountedupon the input shaft 38 for rotation therewith. A pair of cluster gears44 are mounted on opposite sides of input pinion 42 and are in meshingengagement with the input pinion, as best seen in FIGS. 4 and 7. Thecluster gears 44 are each rotatably mounted upon a shaft 46 which issupported by the lower transmission casing 34. Each of the cluster gears44 include an enlarged gear portion 48 and an integrally formed reducedgear portion 50. The enlarged gear portion 48 of each cluster gear 44 isin meshing combination with the input pinion 42.

The reduced gear portion 50 of each cluster gear 44 is in meshingengagement with a crank gear 52. The crank gears 52 are rotatablymounted upon shafts 54 which extend upwardly from the lower transmissioncasing 34 on opposite sides of the input shaft 38.

A pair of rack gears 56 are mounted on the crank gears 52. Each rackgear 56 is connected to the corresponding crank gear 52 by a pin 58extending downwardly from the rack gear and into a hole or aperture 59in the crank gear. The amount of offset of aperture 59 from thecenterline of crank gear 52 controls the degrees of oscillation of theoutput shaft 40. Each rack gear 56 includes a toothed inner side 60 andan untoothed outer side 62. The rack gears 58 extend on opposite sidesof the output shaft 40, and the toothed inner sides 60 are in meshingengagement with an output pinion 64 mounted upon the output shaft 40.

The rack gears 56 are maintained in meshing engagement with the outputpinion 64 by a carrier 66. The carrier 66 has an inverted U-shape incross section, as best seen in FIGS. 4 and 10. The carrier 66 hasopposite side walls 68 which slidably engage the outer sides 62 of therack gears 56, as best seen in FIGS. 4 and 6. The carrier 66 is mountedupon a bushing 70, which in turn is rotatably mounted upon the outputshaft 40. As best seen in FIG. 11, the bushing 70 includes a trunk 72with opposite tabs 74. The trunk 72 is received within a central opening76 of the carrier 66, and the tabs 74 are matingly received within slotsor detents 78 in the carrier 66. As further shown in FIG. 11, thebushing 70 includes slots 75 above the tabs 74. The slots 75 allow oilwhich is pumped up the output shaft 40 during operation to be channeledonto the top of the carrier 66 and returned to the lower portion of thetransmission.

It is critical to the operation of the transmission that the bushing 70float or move side-to-side side with respect to the solidly journaledoutput shaft 40. As best seen in FIG. 3, there is a space 80 between theinner diameter of the bushing 70 and the outer diameter of the outputshaft 40. Preferably, the difference between the inner diameter of thebushing 70 and the outside diameter of the output shaft 40 is at least0.03". This space 80 permits the bushing 70, the carrier 66, and therack gears 56 to float or move side-to-side relative to the output shaft40 and the output pinion 64 so as to equalize the load on the rack gears56. Thus, there is some play between the teeth on the inner side 60 ofthe rack gears 56 and the teeth of the output pinion 64. This floatingmovement of the rack gears 56 relative to the output pinion 64 preventsbinding between the teeth and allows the transmission to run smoothly.It is also important that the centerline of pins 58 and the pitch lineof the teeth of the rack gears 56 are aligned, as shown in FIG. 6, sothat binding and misalignment during operation are minimized.

As seen in FIGS. 8 and 9, as the rack gears 56 oscillate back and forthalong their longitudinal axes, the rack gears 56 slide within thecarrier 66. Also, the rack gears 56 pivotally oscillate about the axisof the output shaft 40, along with the carrier 66, via the bushing 70.The oscillating movement of the rack gears 56 and the rotationalmovement of the carrier 66 are shown in broken lines in FIGS. 8 and 9.More particularly, with respect to FIG. 8, as the crank gear 52 rotatescounterclockwise as indicated by arrows 82, the rack gears 56 andcarrier 66 pivot counterclockwise relative to the axis of the outputshaft as designated by arrow 84, and the rack gears 56 move along theiraxis, as designated by arrow 86, to turn the output pinion 64 in aclockwise direction. As the counterclockwise rotation of the crank gears52 continues, as seen in FIG. 9, the movement of the rack gears 56 andcarrier 60 reverses, so that the rack gears 56 and carrier 60 will pivotin a clockwise direction, as represented by arrow 88, relative to theaxis of the output shaft 40, and the rack gears 56 will move outwardlyalong their longitudinal axes.

As seen in FIG. 4, a cylindrical anti-backup device 90 has a centralbore 92 for mounting the device upon the input shaft 38. The device alsoincludes a pair of radially outwardly projecting spring fingers 94, asbest seen in FIGS. 12 and 13. The fingers 94 cooperate withsubstantially vertically disposed stops or catches 96 on the internalside wall of the transmission housing 26, as more fully described below.

In operation, actuation of the motor (not shown) in one direction turnsthe drive pulley 32 in a similar direction. The drive pulley 32 in turnimparts rotational movement to the input shaft 38, which similarlyrotates the input pinion 42. Rotation of the input pinion 42 turns thecluster gears 44, which, in turn, rotate the crank gears 52. As thecrank gears 52 rotate, the interconnection with the rack gears 56 viathe rack gear pin 58 reciprocates the rack gears 56 in oppositedirections. The reciprocating movement of the rack gears 56 impartsoscillating movement to the output pinion 64, the connected output shaft40, and the agitator 24. Thus, rotational movement from the input shaft38 is converted to oscillating movement of the output shaft 40 throughthe series of gears. As the input shaft 38 rotates in a counterclockwisedirection, as seen in FIG. 13, the fingers 94 of the device 90 biasinwardly as the fingers pass over the stops 96 on the transmissionhousing 26. Thus, the device 90 rotates 360° within the housing 26.

As the load upon the rack gears 56 shifts or changes, the floatingbushing 70 allows the carrier 66 and retained rack gears 56 to moveside-to-side relative to the output pinion 64 and output shaft 40,thereby equalizing the load forces and preventing binding between therack gears 56 and the output pinion 64.

The agitator 24, which is connected to the output shaft 40, thusoscillates upon actuation of the motor in a first direction. When thedrive motor is actuated in the clockwise direction, as seen in FIG. 13,the brake (not shown) is disengaged and the terminal end 98 of thefingers 94 of the device 90 rotate a maximum of 180° and retentivelyengage the stops 96 on the transmission housing 26 to allow the entiretransmission housing 26, the input shaft 38 and the output shaft 40 torotate in the same direction. Thus, the basket 18 will rotate during thespin cycle of the washing machine 10.

In an alternative embodiment, shown in FIG. 14, the gears on one-half ofthe input pinion 42 may be removed to provide a single drivetransmission for use with a smaller machine having less powerrequirements. More particularly, in the alternative embodiment, one ofeach of the pairs of cluster gears 44, crank gears 52, and rack gears 56are eliminated, all on the same side of the input pinion 42. The rackcarrier 66 is still utilized, however, a tighter bushing similar tobushing 70 is utilized to eliminate the float in the remaining rack gear56, and to maintain proper engagement of the rack gear 56 with theoutput pinion 40. For example, the clearance between the single drivebushing and the shaft is preferably 0.001-0.009 inch. The single drivetransmission of the alternative embodiment does not require anyadditional counterbalance weight, since the removed gears are displacedby approximately the same weight of oil.

Whereas the invention has been shown and described in connection withthe preferred embodiments thereof, it will be understood that manymodifications, substitutions, and additions may be made which are withinthe intended broad scope of the following claims. From the foregoing, itcan be seen that the present invention accomplishes at least all of thestated objectives.

What is claimed is:
 1. A transmission for converting a rotary input intoan oscillating output, comprising:a housing having a removable cover; aninput shaft journaled into the housing for inputting rotary motion tothe transmission; an output shaft journaled into the cover foroutputting oscillating motion; an output pinion attached to the outputshaft inside the housing; gearing mounted between the input shaft andthe output shaft within the housing, the gearing including a pair ofrack gears positioned on opposite sides of and in mesh with the outputopinion for converting rotary motion from the input shaft intooscillatory motion of the output shaft; the rack gears having oppositeinner and outer sides with gear teeth on the inner sides; a bushingpivotally mounted on the output shaft between the output shaft and thecover, the bushing being movable by a predetermined side-to-sidedistance relative to the output shaft; and a rack carrier mounted on thebushing for pivotal and side-to-side movement relative to the outputshaft, the rack carrier being in sliding engagement with the outer sidesof the rack gears, the rack carrier retaining the rack gears in meshwith the output pinion while the side-to-side movement of the carrierand bushing relative to the output shaft allows the shifting of the gearteeth of each rack gear relative to the output pinion for equalizing theloading on each rack gear.
 2. The transmission of claim 1 wherein thebushing has at least one tab matingly received in a slot in the rackcarrier such that the bushing and rack carrier pivot together relativeto the output shaft.
 3. The transmission of claim 1 wherein the rackcarrier has a generally inverted U-shaped cross section with oppositeside walls of the U-shape being in sliding engagement with the outersides of the rack gears.
 4. The transmission of claim 1 wherein one ofthe rack gears is removable to provide a single drive transmission. 5.The transmission of claim 1 wherein the teeth of each rack gear define apitch line, and each rack gear being pivotally mounted upon a crank gearat a pivot point aligned with the pitch line.
 6. The transmission ofclaim 1 further comprising an anti-backup mechanism mounted upon theinput shaft, the housing having at least two stops on an inner surfacethereof, the anti-backup mechanism having points of engagement with thestops of the housing to lock the housing to the input shaft uponrotation of the input shaft in a first direction.
 7. The transmission ofclaim 6 wherein the points of engagement are defined by a pair of springfingers which retentively engage the stops upon rotation of the inputshaft in the first direction, and which bias away from the stops whenthe input shaft rotates in the opposite direction.
 8. A transmission forconverting a rotary input into an oscillating output, comprising:ahousing having a removable cover; an input shaft rotatably extendinginto the housing for inputting rotary motion to the transmission; anoutput shaft rotatably extending into the cover for outputtingoscillating motion; an output pinion attached to the output shaft insidethe housing; gearing mounted between the input shaft and the outputshaft within the housing, the gearing including a pair of rack gearspositioned on opposite sides of and in mesh with the output pinion forconverting rotary motion from the input shaft into oscillatory motion ofthe output shaft; the rack gears having opposite inner and outer sideswith gear teeth on the inner sides; a carrier including a bushing, andbeing mounted on the output shaft, the carrier and bushing beingcooperable for maintaining the rack gears in mesh with the outputpinion; the rack gears being movable side-to-side within the carrierrelative to the output pinion to prevent binding between the rack gearsand the output pinion.
 9. The transmission of claim 8 wherein thecarrier slidably extends over the outer sides of the rack gears tomaintain the rack gears in meshing engagement with the output pinion.10. The transmission of claim 8 wherein the bushing is pivotally mountedon the output shaft and supports the carrier.
 11. The transmission ofclaim 8 wherein the bushing and the output shaft have clearancetherebetween to allow side-to-side movement of the bushing relative tothe output shaft, and thereby side-to-side movement of the teeth of thegear rack relative to the output pinion.
 12. The transmission of claim 8wherein one of the rack gears is removable to provide a single drivetransmission.
 13. The transmission of claim 8 wherein the teeth of eachrack gear defines a pitch line, and each rack gear being pivotallymounted upon a crank gear at a pivot point aligned with the pitch line.14. The transmission of claim 8 further comprising an anti-backupmechanism mounted upon the input shaft, the housing having at least twostops on an inner surface thereof, the anti-backup mechanism havingpoints of engagement with the stops of the housing to lock the housingto the input shaft upon rotation of the input shaft in a firstdirection.
 15. The transmission of claim 14 wherein the points ofengagement are defined by a pair of spring fingers which retentivelyengage the stops upon rotation of the input shaft in the firstdirection, and which bias away from the stops when the input shaftrotates in the opposite direction.
 16. A method of converting rotarymotion to oscillating motion in a transmission having a housing with aremovable cover, an input shaft journaled into the housing for inputtingrotary motion to the transmission, an output shaft journaled into thecover for outputting oscillating motion, an output gear attached to theoutput shaft inside the housing, intermediate gearing between the inputand output shafts including a pair of rack gears positioned on oppositesides of and in mesh with the output gear for converting rotary motionfrom the input shaft into oscillatory motion of the output shaft, themethod comprising:rotating the input shaft in one direction, therebyoscillating the rack gears, the meshed output gear and the output shaft;equalizing the loading on each rack gear by limiting the side-to-sidemovement of the rack gears with a rack carrier extending over the rackgears and mounted upon a bushing floatably journaled on the output shaftthereby preventing binding between the rack gears and the output gear.17. The method of claim 16 wherein the load equalization is accomplishedby allowing the rack gears to move side-to-side relative to the outputgear while maintaining meshing engagement therebetween.
 18. The methodof claim 16 further comprising rotating the input shaft in an oppositedirection, thereby rotating the housing, input shaft and output shaft inunison in the opposite direction.
 19. The method of claim 16 wherein therack gears each have a pivot axis and a plurality of teeth defining apitch line, the method further comprising aligning the pivot axis ofeach rack gear with the pitch line of the teeth of the rack gear. 20.The method of claim 18 further comprising engaging an anti-backupmechanism with a stop element on the housing upon rotation of the inputshaft in the opposite direction.
 21. A transmission for converting arotary input into an oscillating output, comprising:a housing having aremovable cover; an input shaft journaled into the housing for inputtingrotary motion to the transmission; an output shaft journaled into thecover for outputting oscillating motion; an output pinion attached tothe output shaft inside the housing; gearing mounted between the inputshaft and the output shaft within the housing, the gearing including afirst rack gear positioned in mesh with the output pinion for convertingrotary motion from the input shaft into oscillatory motion of the outputshaft; the rack gear having opposite inner and outer sides with gearteeth on the inner side; a bushing pivotally mounted on the output shaftbetween the output shaft and the cover, the bushing being movable by apredetermined side-to-side distance relative to the output shaft; and arack carrier mounted on the bushing for pivotal movement relative to theoutput shaft, the rack carrier being in sliding engagement with theouter side of the rack gear, the rack carrier retaining the rack gear inmesh with the output pinion.
 22. The transmission of claim 21 furthercomprising a second rack gear positioned in mesh with the output pinionand on the opposite side of the out pinion as the first rack gear. 23.The transmission of claim 21 wherein the rack carrier has side-to-sidemovement relative to the output shaft to equalize the load on each rackgear.